passt: Add clang-tidy Makefile target and test, take care of warnings

Most are just about style and form, but a few were actually
serious mistakes (NDP-related).

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

14 files changed, 172 insertions, 73 deletions

diff --git a/Makefile b/Makefile
index 6d11e22..85d7400 100644
--- a/Makefile
+++ b/Makefile
@@ -87,3 +87,78 @@ pkgs:
 	fakeroot alien --to-rpm --target=$(shell uname -m) \
 		--description="User-mode networking for VMs and namespaces" \
 		-k --version=g$(shell git rev-parse --short HEAD) passt.tar.gz
+
+# Checkers currently disabled for clang-tidy:
+# - llvmlibc-restrict-system-libc-headers
+#	TODO: this is Linux-only for the moment, nice to fix eventually
+#
+# - bugprone-macro-parentheses
+# - google-readability-braces-around-statements
+# - hicpp-braces-around-statements
+# - readability-braces-around-statements
+#	Debatable whether that improves readability, right now it would look
+#	like a mess
+#
+# - readability-magic-numbers
+# - cppcoreguidelines-avoid-magic-numbers
+#	TODO: in most cases they are justified, but probably not everywhere
+#
+# - clang-analyzer-valist.Uninitialized
+#	TODO: enable once https://bugs.llvm.org/show_bug.cgi?id=41311 is fixed
+#
+# - clang-analyzer-security.insecureAPI.DeprecatedOrUnsafeBufferHandling
+#	Probably not doable to impement this without plain memcpy(), memset()
+#
+# - cppcoreguidelines-init-variables
+#	Dubious value, would kill readability
+#
+# - hicpp-signed-bitwise
+#	Those are needed for syscalls, epoll_wait flags, etc.
+#
+# - bugprone-reserved-identifier,cert-dcl37-c,cert-dcl51-cpp
+#	This flags _GNU_SOURCE, currently needed
+#
+# - llvm-include-order
+#	TODO: not really important, but nice to fix eventually
+#
+# - readability-isolate-declaration
+#	Dubious value, would kill readability
+#
+# - android-cloexec-open
+# - android-cloexec-pipe
+# - android-cloexec-pipe2
+# - android-cloexec-epoll-create1
+#	TODO: check, fix except for the few cases where we need to share fds
+#
+# - bugprone-narrowing-conversions
+# - cppcoreguidelines-narrowing-conversions
+#	TODO: nice to fix eventually
+#
+# - cppcoreguidelines-avoid-non-const-global-variables
+#	TODO: check, fix, and more in general constify wherever possible
+#
+# - bugprone-suspicious-string-compare
+#	Return value of memcmp(), not really suspicious
+clang-tidy: $(wildcard *.c)
+	clang-tidy -checks=*,-modernize-*,\
+	-clang-analyzer-valist.Uninitialized,\
+	-cppcoreguidelines-init-variables,\
+	-bugprone-macro-parentheses,\
+	-google-readability-braces-around-statements,\
+	-hicpp-braces-around-statements,\
+	-readability-braces-around-statements,\
+	-readability-magic-numbers,\
+	-llvmlibc-restrict-system-libc-headers,\
+	-hicpp-signed-bitwise,\
+	-bugprone-reserved-identifier,-cert-dcl37-c,-cert-dcl51-cpp,\
+	-clang-analyzer-security.insecureAPI.DeprecatedOrUnsafeBufferHandling,\
+	-llvm-include-order,\
+	-cppcoreguidelines-avoid-magic-numbers,\
+	-readability-isolate-declaration,\
+	-android-cloexec-open,-android-cloexec-pipe,-android-cloexec-pipe2,\
+	-android-cloexec-epoll-create1,\
+	-bugprone-narrowing-conversions,\
+	-cppcoreguidelines-narrowing-conversions,\
+	-cppcoreguidelines-avoid-non-const-global-variables,\
+	-bugprone-suspicious-string-compare \
+	--warnings-as-errors=* $(wildcard *.c) -- $(CFLAGS)
diff --git a/conf.c b/conf.c
index 2fb58a7..13d3dc6 100644
--- a/conf.c
+++ b/conf.c
@@ -912,10 +912,6 @@ void conf(struct ctx *c, int argc, char **argv)
 
 			c->foreground = 1;
 			break;
-		case '?':
-		case 'h':
-			usage(argv[0]);
-			break;
 		case 's':
 			if (*c->sock_path) {
 				err("Multiple --socket options given");
@@ -1142,6 +1138,11 @@ void conf(struct ctx *c, int argc, char **argv)
 				usage(argv[0]);
 
 			break;
+		case '?':
+		case 'h':
+		default:
+			usage(argv[0]);
+			break;
 		}
 	} while (name != -1);
 
diff --git a/dhcp.c b/dhcp.c
index 7deced1..5c74604 100644
--- a/dhcp.c
+++ b/dhcp.c
@@ -225,9 +225,8 @@ static void opt_set_dns_search(struct ctx *c, size_t max_len)
 					buf[n++] = '\xc0';
 					buf[n++] = dup;
 					break;
-				} else {
-					buf[n++] = '.';
 				}
+				buf[n++] = '.';
 			} else {
 				buf[n++] = *p;
 			}
diff --git a/icmp.c b/icmp.c
index 51848c2..7d7b688 100644
--- a/icmp.c
+++ b/icmp.c
@@ -254,11 +254,11 @@ void icmp_timer(struct ctx *c, struct timespec *ts)
 
 v6:
 	word = (long *)icmp_act[v6 ? V6 : V4];
-	for (i = 0; i < sizeof(icmp_act[0]) / sizeof(long); i++, word++) {
+	for (i = 0; i < ARRAY_SIZE(icmp_act); i += sizeof(long), word++) {
 		tmp = *word;
 		while ((n = ffsl(tmp))) {
 			tmp &= ~(1UL << (n - 1));
-			icmp_timer_one(c, v6, i * sizeof(long) * 8 + n - 1, ts);
+			icmp_timer_one(c, v6, i * 8 + n - 1, ts);
 		}
 	}
 
diff --git a/ndp.c b/ndp.c
index e18d4cc..10c091c 100644
--- a/ndp.c
+++ b/ndp.c
@@ -53,7 +53,7 @@ int ndp(struct ctx *c, struct ethhdr *eh, size_t len)
 	char buf[BUFSIZ] = { 0 };
 	uint8_t proto, *p;
 
-	if (len < sizeof(*ehr) + sizeof(*ip6h) + sizeof(ih))
+	if (len < sizeof(*ehr) + sizeof(*ip6h) + sizeof(*ih))
 		return 0;
 
 	ih = (struct icmp6hdr *)ipv6_l4hdr(ip6h, &proto);
@@ -72,7 +72,7 @@ int ndp(struct ctx *c, struct ethhdr *eh, size_t len)
 	ihr = (struct icmp6hdr *)(ip6hr + 1);
 
 	if (ih->icmp6_type == NS) {
-		if (len < sizeof(*ehr) + sizeof(*ip6h) + sizeof(ih) +
+		if (len < sizeof(*ehr) + sizeof(*ip6h) + sizeof(*ih) +
 			  sizeof(struct in6_addr))
 			return -1;
 
diff --git a/netlink.c b/netlink.c
index 2e72568..2b6118b 100644
--- a/netlink.c
+++ b/netlink.c
@@ -97,13 +97,15 @@ int nl_sock_init(struct ctx *c)
  */
 static int nl_req(int ns, char *buf, void *req, ssize_t len)
 {
-	int n, s = ns ? nl_sock_ns : nl_sock, done = 0;
+	int s = ns ? nl_sock_ns : nl_sock, done = 0;
 	char flush[BUFSIZ];
+	ssize_t n;
 
 	while (!done && (n = recv(s, flush, sizeof(flush), MSG_DONTWAIT)) > 0) {
 		struct nlmsghdr *nh = (struct nlmsghdr *)flush;
+		size_t nm = n;
 
-		for ( ; NLMSG_OK(nh, n); nh = NLMSG_NEXT(nh, n)) {
+		for ( ; NLMSG_OK(nh, nm); nh = NLMSG_NEXT(nh, nm)) {
 			if (nh->nlmsg_type == NLMSG_DONE ||
 			    nh->nlmsg_type == NLMSG_ERROR) {
 				done = 1;
@@ -129,7 +131,7 @@ unsigned int nl_get_ext_if(int *v4, int *v6)
 {
 	struct { struct nlmsghdr nlh; struct rtmsg rtm; } req = {
 		.nlh.nlmsg_type	 = RTM_GETROUTE,
-		.nlh.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP | NLM_F_EXCL,
+		.nlh.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP,
 		.nlh.nlmsg_len	 = NLMSG_LENGTH(sizeof(struct rtmsg)),
 		.nlh.nlmsg_seq	 = nl_seq++,
 
@@ -145,8 +147,9 @@ unsigned int nl_get_ext_if(int *v4, int *v6)
 	struct rtmsg *rtm;
 	char buf[BUFSIZ];
 	long *word, tmp;
-	int n, na, *v;
 	uint8_t *vmap;
+	size_t n, na;
+	int *v;
 
 	if (*v4 == IP_VERSION_PROBE) {
 		v = v4;
@@ -170,8 +173,8 @@ v6:
 		if (rtm->rtm_dst_len || rtm->rtm_family != req.rtm.rtm_family)
 			continue;
 
-		for (rta = (struct rtattr *)RTM_RTA(rtm), na = RTM_PAYLOAD(nh);
-		     RTA_OK(rta, na); rta = RTA_NEXT(rta, na)) {
+		for (rta = RTM_RTA(rtm), na = RTM_PAYLOAD(nh); RTA_OK(rta, na);
+		     rta = RTA_NEXT(rta, na)) {
 			unsigned int ifi;
 
 			if (rta->rta_type != RTA_OIF)
@@ -283,7 +286,7 @@ void nl_route(int ns, unsigned int ifi, sa_family_t af, void *gw)
 	struct rtattr *rta;
 	struct rtmsg *rtm;
 	char buf[BUFSIZ];
-	int n, na;
+	size_t n, na;
 
 	if (set) {
 		if (af == AF_INET6) {
@@ -326,8 +329,8 @@ void nl_route(int ns, unsigned int ifi, sa_family_t af, void *gw)
 		if (rtm->rtm_dst_len)
 			continue;
 
-		for (rta = (struct rtattr *)RTM_RTA(rtm), na = RTM_PAYLOAD(nh);
-		     RTA_OK(rta, na); rta = RTA_NEXT(rta, na)) {
+		for (rta = RTM_RTA(rtm), na = RTM_PAYLOAD(nh); RTA_OK(rta, na);
+		     rta = RTA_NEXT(rta, na)) {
 			if (rta->rta_type != RTA_GATEWAY)
 				continue;
 
@@ -388,7 +391,7 @@ void nl_addr(int ns, unsigned int ifi, sa_family_t af,
 	struct nlmsghdr *nh;
 	struct rtattr *rta;
 	char buf[BUFSIZ];
-	int n, na;
+	size_t n, na;
 
 	if (set) {
 		if (af == AF_INET6) {
@@ -429,8 +432,8 @@ void nl_addr(int ns, unsigned int ifi, sa_family_t af,
 		if (ifa->ifa_index != ifi)
 			goto next;
 
-		for (rta = (struct rtattr *)IFA_RTA(ifa), na = RTM_PAYLOAD(nh);
-		     RTA_OK(rta, na); rta = RTA_NEXT(rta, na)) {
+		for (rta = IFA_RTA(ifa), na = RTM_PAYLOAD(nh); RTA_OK(rta, na);
+		     rta = RTA_NEXT(rta, na)) {
 			if (rta->rta_type != IFA_ADDRESS)
 				continue;
 
@@ -487,7 +490,7 @@ void nl_link(int ns, unsigned int ifi, void *mac, int up, int mtu)
 	struct nlmsghdr *nh;
 	struct rtattr *rta;
 	char buf[BUFSIZ];
-	int n, na;
+	size_t n, na;
 
 	if (!MAC_IS_ZERO(mac)) {
 		req.nlh.nlmsg_len = sizeof(req);
@@ -522,8 +525,8 @@ void nl_link(int ns, unsigned int ifi, void *mac, int up, int mtu)
 
 		ifm = (struct ifinfomsg *)NLMSG_DATA(nh);
 
-		for (rta = (struct rtattr *)IFLA_RTA(ifm), na = RTM_PAYLOAD(nh);
-		     RTA_OK(rta, na); rta = RTA_NEXT(rta, na)) {
+		for (rta = IFLA_RTA(ifm), na = RTM_PAYLOAD(nh); RTA_OK(rta, na);
+		     rta = RTA_NEXT(rta, na)) {
 			if (rta->rta_type != IFLA_ADDRESS)
 				continue;
 
diff --git a/pasta.c b/pasta.c
index 395f459..3febfd5 100644
--- a/pasta.c
+++ b/pasta.c
@@ -204,7 +204,7 @@ void pasta_start_ns(struct ctx *c)
 		close(fd);
 
 		fd = open("/proc/self/setgroups", O_WRONLY);
-		if (write(fd, "deny", sizeof("deny")))
+		if (write(fd, "deny", sizeof("deny")) < 0)
 			warn("Cannot write to setgroups in namespace");
 		close(fd);
 
diff --git a/tcp.c b/tcp.c
index de28891..c8815c5 100644
--- a/tcp.c
+++ b/tcp.c
@@ -511,7 +511,7 @@ struct tcp_tap_conn {
 	struct timespec ts_ack_to_tap;
 	struct timespec tap_data_noack;
 
-	int mss_guest;
+	unsigned int mss_guest;
 
 	uint32_t events;
 };
@@ -898,7 +898,7 @@ static void tcp_update_check_tcp6(struct tcp6_l2_buf_t *buf)
  * @ip_da:	Pointer to IPv4 destination address, NULL if unchanged
  */
 void tcp_update_l2_buf(unsigned char *eth_d, unsigned char *eth_s,
-		       uint32_t *ip_da)
+		       const uint32_t *ip_da)
 {
 	int i;
 
@@ -1452,7 +1452,7 @@ void tcp_defer_handler(struct ctx *c)
  */
 static size_t tcp_l2_buf_fill_headers(struct ctx *c, struct tcp_tap_conn *conn,
 				      void *p, size_t plen,
-				      uint16_t *check, uint32_t seq)
+				      const uint16_t *check, uint32_t seq)
 {
 	size_t ip_len, eth_len;
 
@@ -1582,7 +1582,7 @@ static int tcp_update_seqack_wnd(struct ctx *c, struct tcp_tap_conn *conn,
 		conn->wnd_to_tap = info->tcpi_snd_wnd;
 	} else {
 		tcp_get_sndbuf(conn);
-		conn->wnd_to_tap = MIN(info->tcpi_snd_wnd, conn->snd_buf);
+		conn->wnd_to_tap = MIN((int)info->tcpi_snd_wnd, conn->snd_buf);
 	}
 
 	conn->wnd_to_tap = MIN(conn->wnd_to_tap, MAX_WINDOW);
@@ -1622,7 +1622,7 @@ static int tcp_send_to_tap(struct ctx *c, struct tcp_tap_conn *conn, int flags,
 		return 0;
 
 	if (getsockopt(s, SOL_TCP, TCP_INFO, &info, &sl)) {
-		tcp_rst(c, conn);
+		tcp_tap_destroy(c, conn);
 		return -ECONNRESET;
 	}
 
@@ -1658,7 +1658,7 @@ static int tcp_send_to_tap(struct ctx *c, struct tcp_tap_conn *conn, int flags,
 		if (c->mtu == -1) {
 			mss = info.tcpi_snd_mss;
 		} else {
-			mss = c->mtu - sizeof(sizeof *th);
+			mss = c->mtu - sizeof(struct tcphdr);
 			if (CONN_V4(conn))
 				mss -= sizeof(struct iphdr);
 			else
@@ -1880,9 +1880,9 @@ static void tcp_conn_from_tap(struct ctx *c, int af, void *addr,
 		.sin6_addr = *(struct in6_addr *)addr,
 	};
 	union epoll_ref ref = { .proto = IPPROTO_TCP };
+	int i, s, *sock_pool_p, mss;
 	const struct sockaddr *sa;
 	struct tcp_tap_conn *conn;
-	int i, s, *sock_pool_p;
 	struct epoll_event ev;
 	socklen_t sl;
 
@@ -1921,7 +1921,10 @@ static void tcp_conn_from_tap(struct ctx *c, int af, void *addr,
 			.sin6_addr = c->addr6_ll,
 			.sin6_scope_id = c->ifi,
 		};
-		bind(s, (struct sockaddr *)&addr6_ll, sizeof(addr6_ll));
+		if (bind(s, (struct sockaddr *)&addr6_ll, sizeof(addr6_ll))) {
+			close(s);
+			return;
+		}
 	}
 
 	conn = &tt[c->tcp.tap_conn_count++];
@@ -1930,9 +1933,10 @@ static void tcp_conn_from_tap(struct ctx *c, int af, void *addr,
 
 	conn->wnd_to_tap = WINDOW_DEFAULT;
 
-	conn->mss_guest = tcp_opt_get(th, len, OPT_MSS, NULL, NULL);
-	if (conn->mss_guest < 0)
+	if ((mss = tcp_opt_get(th, len, OPT_MSS, NULL, NULL)) < 0)
 		conn->mss_guest = MSS_DEFAULT;
+	else
+		conn->mss_guest = mss;
 
 	/* Don't upset qemu */
 	if (c->mode == MODE_PASST) {
@@ -2186,9 +2190,8 @@ static int tcp_data_from_sock(struct ctx *c, struct tcp_tap_conn *conn,
 	iov_sock[0].iov_base = tcp_buf_discard;
 	iov_sock[0].iov_len = already_sent;
 
-	if (v4 && tcp4_l2_buf_used + fill_bufs > ARRAY_SIZE(tcp4_l2_buf))
-		tcp_l2_buf_flush(c);
-	else if (!v4 && tcp6_l2_buf_used + fill_bufs > ARRAY_SIZE(tcp6_l2_buf))
+	if (( v4 && tcp4_l2_buf_used + fill_bufs > ARRAY_SIZE(tcp4_l2_buf)) ||
+	    (!v4 && tcp6_l2_buf_used + fill_bufs > ARRAY_SIZE(tcp6_l2_buf)))
 		tcp_l2_buf_flush(c);
 
 	for (i = 0, iov = iov_sock + 1; i < fill_bufs; i++, iov++) {
@@ -2543,6 +2546,7 @@ int tcp_tap_handler(struct ctx *c, int af, void *addr,
 	struct tcphdr *th = (struct tcphdr *)(pkt_buf + msg[0].pkt_buf_offset);
 	uint16_t len = msg[0].l4_len;
 	struct tcp_tap_conn *conn;
+	int mss;
 
 	conn = tcp_hash_lookup(c, af, addr, htons(th->source), htons(th->dest));
 	if (!conn) {
@@ -2567,9 +2571,10 @@ int tcp_tap_handler(struct ctx *c, int af, void *addr,
 
 		tcp_clamp_window(conn, th, len, 0, 1);
 
-		conn->mss_guest = tcp_opt_get(th, len, OPT_MSS, NULL, NULL);
-		if (conn->mss_guest < 0)
+		if ((mss = tcp_opt_get(th, len, OPT_MSS, NULL, NULL)) < 0)
 			conn->mss_guest = MSS_DEFAULT;
+		else
+			conn->mss_guest = mss;
 
 		/* Don't upset qemu */
 		if (c->mode == MODE_PASST) {
@@ -2936,7 +2941,7 @@ static void tcp_conn_from_sock(struct ctx *c, union epoll_ref ref,
 		in_addr_t s_addr;
 
 		memcpy(&sa4, &sa, sizeof(sa4));
-		s_addr = sa4.sin_addr.s_addr;
+		s_addr = ntohl(sa4.sin_addr.s_addr);
 
 		memset(&conn->a.a4.zero,   0, sizeof(conn->a.a4.zero));
 		memset(&conn->a.a4.one, 0xff, sizeof(conn->a.a4.one));
@@ -3156,9 +3161,12 @@ eintr:
 			ev.data.u64 = ref.u64,
 			epoll_ctl(c->epollfd, EPOLL_CTL_MOD, move_to, &ev);
 			break;
-		} else if (never_read && written == (long)(c->tcp.pipe_size)) {
+		}
+
+		if (never_read && written == (long)(c->tcp.pipe_size))
 			goto retry;
-		} else if (!never_read && written < to_write) {
+
+		if (!never_read && written < to_write) {
 			to_write -= written;
 			goto retry;
 		}
@@ -3221,7 +3229,6 @@ close:
 	epoll_ctl(c->epollfd, EPOLL_CTL_DEL, conn->from, NULL);
 	epoll_ctl(c->epollfd, EPOLL_CTL_DEL, conn->to, NULL);
 	conn->state = CLOSED;
-	return;
 }
 
 /**
@@ -3448,7 +3455,7 @@ static void tcp_sock_init_one(struct ctx *c, int ns, in_port_t port)
 static int tcp_sock_init_ns(void *arg)
 {
 	struct ctx *c = (struct ctx *)arg;
-	in_port_t port;
+	int port;
 
 	ns_enter(c);
 
@@ -3550,8 +3557,7 @@ static int tcp_sock_refill(void *arg)
 int tcp_sock_init(struct ctx *c, struct timespec *now)
 {
 	struct tcp_sock_refill_arg refill_arg = { c, 0 };
-	in_port_t port;
-	int i;
+	int i, port;
 
 	if (getrandom(&c->tcp.hash_secret, sizeof(c->tcp.hash_secret),
 		      GRND_RANDOM) < 0) {
@@ -3646,9 +3652,7 @@ static void tcp_timer_one(struct ctx *c, struct tcp_tap_conn *conn,
 			break;
 		}
 
-		if (!conn->wnd_to_tap)
-			tcp_send_to_tap(c, conn, 0, ts);
-		else if (ack_to_tap > ACK_INTERVAL)
+		if (!conn->wnd_to_tap || ack_to_tap > ACK_INTERVAL)
 			tcp_send_to_tap(c, conn, 0, ts);
 
 		if (tap_data_noack > ACK_TIMEOUT) {
@@ -3673,9 +3677,7 @@ static void tcp_timer_one(struct ctx *c, struct tcp_tap_conn *conn,
 			tcp_rst(c, conn);
 		break;
 	case LAST_ACK:
-		if (sock_act > LAST_ACK_TIMEOUT)
-			tcp_rst(c, conn);
-		else if (tap_act > LAST_ACK_TIMEOUT)
+		if (sock_act > LAST_ACK_TIMEOUT || tap_act > LAST_ACK_TIMEOUT)
 			tcp_rst(c, conn);
 		break;
 	case TAP_SYN_SENT:
@@ -3739,7 +3741,7 @@ struct tcp_port_rebind_arg {
 static int tcp_port_rebind(void *arg)
 {
 	struct tcp_port_rebind_arg *a = (struct tcp_port_rebind_arg *)arg;
-	in_port_t port;
+	int port;
 
 	if (a->bind_in_ns) {
 		ns_enter(a->c);
@@ -3808,7 +3810,7 @@ static int tcp_port_rebind(void *arg)
 /**
  * tcp_timer() - Scan activity bitmap for sockets waiting for timed events
  * @c:		Execution context
- * @ts:		Timestamp from caller
+ * @now:	Timestamp from caller
  */
 void tcp_timer(struct ctx *c, struct timespec *now)
 {
diff --git a/tcp.h b/tcp.h
index d59bc81..bfd6082 100644
--- a/tcp.h
+++ b/tcp.h
@@ -18,10 +18,10 @@ void tcp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events,
 int tcp_tap_handler(struct ctx *c, int af, void *addr,
 		    struct tap_l4_msg *msg, int count, struct timespec *now);
 int tcp_sock_init(struct ctx *c, struct timespec *now);
-void tcp_timer(struct ctx *c, struct timespec *ts);
+void tcp_timer(struct ctx *c, struct timespec *now);
 void tcp_defer_handler(struct ctx *c);
 void tcp_update_l2_buf(unsigned char *eth_d, unsigned char *eth_s,
-		       uint32_t *ip_da);
+		       const uint32_t *ip_da);
 void tcp_remap_to_tap(in_port_t port, in_port_t delta);
 void tcp_remap_to_init(in_port_t port, in_port_t delta);
 
diff --git a/test/build/static_checkers b/test/build/static_checkers
new file mode 100644
index 0000000..6e080b4
--- /dev/null
+++ b/test/build/static_checkers
@@ -0,0 +1,18 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
+#
+# PASST - Plug A Simple Socket Transport
+#  for qemu/UNIX domain socket mode
+#
+# PASTA - Pack A Subtle Tap Abstraction
+#  for network namespace/tap device mode
+#
+# test/build/clang_tidy - Run source through clang-tidy(1) linter
+#
+# Copyright (c) 2021 Red Hat GmbH
+# Author: Stefano Brivio <sbrivio@redhat.com>
+
+htools	clang-tidy
+
+test	Run clang-tidy
+hout	RET make clang-tidy; echo $?
+check	[ __RET__ -eq 0 ]
diff --git a/udp.c b/udp.c
index 0703fc9..bd03036 100644
--- a/udp.c
+++ b/udp.c
@@ -319,7 +319,7 @@ static void udp_update_check4(struct udp4_l2_buf_t *buf)
  * @ip_da:	Pointer to IPv4 destination address, NULL if unchanged
  */
 void udp_update_l2_buf(unsigned char *eth_d, unsigned char *eth_s,
-		       uint32_t *ip_da)
+		       const uint32_t *ip_da)
 {
 	int i;
 
@@ -1017,7 +1017,7 @@ int udp_sock_init_ns(void *arg)
 {
 	union udp_epoll_ref uref = { .bound = 1, .splice = UDP_TO_INIT };
 	struct ctx *c = (struct ctx *)arg;
-	in_port_t dst;
+	int dst;
 
 	ns_enter(c);
 
@@ -1105,8 +1105,7 @@ static void udp_splice_iov_init(void)
 int udp_sock_init(struct ctx *c, struct timespec *now)
 {
 	union udp_epoll_ref uref = { .bound = 1 };
-	in_port_t dst;
-	int s;
+	int dst, s;
 
 	(void)now;
 
@@ -1224,21 +1223,22 @@ void udp_timer(struct ctx *c, struct timespec *ts)
 	unsigned int i;
 	long *word, tmp;
 
+	if (!c->v4)
+		v6 = 1;
 v6:
 	for (t = 0; t < UDP_ACT_TYPE_MAX; t++) {
 		word = (long *)udp_act[v6 ? V6 : V4][t];
-		for (i = 0; i < sizeof(udp_act[0][0]) / sizeof(long);
-		     i++, word++) {
+		for (i = 0; i < ARRAY_SIZE(udp_act[0][0]);
+		     i += sizeof(long), word++) {
 			tmp = *word;
 			while ((n = ffsl(tmp))) {
 				tmp &= ~(1UL << (n - 1));
-				udp_timer_one(c, v6, t,
-					      i * sizeof(long) * 8 + n - 1, ts);
+				udp_timer_one(c, v6, t, i * 8 + n - 1, ts);
 			}
 		}
 	}
 
-	if (!v6) {
+	if (!v6 && c->v6) {
 		v6 = 1;
 		goto v6;
 	}
diff --git a/udp.h b/udp.h
index e2d394c..8be174f 100644
--- a/udp.h
+++ b/udp.h
@@ -15,7 +15,7 @@ int udp_tap_handler(struct ctx *c, int af, void *addr,
 int udp_sock_init(struct ctx *c, struct timespec *now);
 void udp_timer(struct ctx *c, struct timespec *ts);
 void udp_update_l2_buf(unsigned char *eth_d, unsigned char *eth_s,
-		       uint32_t *ip_da);
+		       const uint32_t *ip_da);
 void udp_remap_to_tap(in_port_t port, in_port_t delta);
 void udp_remap_to_init(in_port_t port, in_port_t delta);
 
diff --git a/util.c b/util.c
index 56b256d..4c2e9bb 100644
--- a/util.c
+++ b/util.c
@@ -143,7 +143,7 @@ void passt_vsyslog(int pri, const char *format, va_list ap)
 		n += snprintf(buf + n, BUFSIZ - n, "\n");
 
 	if (log_opt | LOG_PERROR)
-		fprintf(stderr, buf + sizeof("<0>"));
+		fprintf(stderr, "%s", buf + sizeof("<0>"));
 
 	send(log_sock, buf, n, 0);
 }
@@ -362,7 +362,7 @@ void bitmap_clear(uint8_t *map, int bit)
  *
  * Return: non-zero if given bit is set, zero if it's not
  */
-int bitmap_isset(uint8_t *map, int bit)
+int bitmap_isset(const uint8_t *map, int bit)
 {
 	return map[bit / 8] & (1 << bit % 8);
 }
@@ -437,6 +437,7 @@ void procfs_scan_listen(char *name, uint8_t *map, uint8_t *exclude)
 	*line = 0;
 	line_read(line, sizeof(line), fd);
 	while (line_read(line, sizeof(line), fd)) {
+		/* NOLINTNEXTLINE(cert-err34-c): != 2 if conversion fails */
 		if (sscanf(line, "%*u: %*x:%lx %*x:%*x %x", &port, &state) != 2)
 			continue;
 
diff --git a/util.h b/util.h
index 44ba980..1fc2983 100644
--- a/util.h
+++ b/util.h
@@ -36,7 +36,7 @@ void debug(const char *format, ...);
 
 #define SWAP(a, b)							\
 	do {								\
-		typeof(a) __x = (a); (a) = (b); (b) = __x;		\
+		__typeof__(a) __x = (a); (a) = (b); (b) = __x;		\
 	} while (0)							\
 
 #define STRINGIFY(x)	#x
@@ -152,7 +152,7 @@ enum bind_type {
 struct ctx;
 
 void __openlog(const char *ident, int option, int facility);
-void passt_vsyslog(int pri, const char *fmt, va_list ap);
+void passt_vsyslog(int pri, const char *format, va_list ap);
 void __setlogmask(int mask);
 char *ipv6_l4hdr(struct ipv6hdr *ip6h, uint8_t *proto);
 int sock_l4(struct ctx *c, int af, uint8_t proto, uint16_t port,
@@ -161,7 +161,7 @@ void sock_probe_mem(struct ctx *c);
 int timespec_diff_ms(struct timespec *a, struct timespec *b);
 void bitmap_set(uint8_t *map, int bit);
 void bitmap_clear(uint8_t *map, int bit);
-int bitmap_isset(uint8_t *map, int bit);
+int bitmap_isset(const uint8_t *map, int bit);
 char *line_read(char *buf, size_t len, int fd);
 void procfs_scan_listen(char *name, uint8_t *map, uint8_t *exclude);
 int ns_enter(struct ctx *c);